Rinnai ENERGYSAVER EX08C Installation Fundamentals page 59

ES38 Vent and Gas Connection Differences
Shipped with each ES38 is a vent adaptor that
reduces the 50 mm diameter exhaust to 30
mm for connection to vent termination.
NOTE: If using extension sets, this reducer
must be connected to the VENT
TERMINATION ONLY! Do not use the
smaller extension sets with this reducer
installed at the furnace. The ES38 will not
operate correctly.
Included with the ES38 is male
to female "street" elbow to
attach to the unit before a
union or flex line. This allows
the installer to select the
direction in which the gas line
will be connected.
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